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Title: On the composition of bimetallic near-surface alloys in the presence of oxygen and carbon monoxide

Abstract

Periodic, self-consistent density functional theory calculations (GGA-PW91) are used to examine surface segregation in close-packed bimetallic Pt-overlayer alloy surfaces (Pt*/M, M = Au, Ag, Cu, Pd, Ir, Rh, Os, Ru, and Re) in different environments. In particular, we find that the thermodynamically stable surface termination in these Pt*/M alloys can be inverted from Pt-terminated in vacuum to M-terminated under exposure to oxygen (for an M that is more oxophillic than Pt). Interestingly, in many of these alloys, Pt is not driven into the bulk, rather it remains in the first subsurface layer where it enhances oxygen binding through a ligand interaction with the surface metal atoms. On the other hand, exposure to CO provides a much milder driving force for the surface composition inversion. To quantify segregation under catalytically relevant conditions, we constructed approximate phase diagrams for the PtRu systemas a function of O 2 and CO chemical potential (temperature, pressure). Lastly, the results show that the surface termination inverts with many orders of magnitude higher CO pressure than with O 2.

Authors:
 [1];  [1]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemical and Biological Engineering
Publication Date:
Research Org.:
Univ. of Wisconsin-Madison, Madison, WI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Org.:
EMSL, a National scientific user facility at Pacific Northwest National Laboratory (PNNL); the Center for Nanoscale Materials at Argonne National Laboratory (ANL); and the National Energy Research Scientific Computing Center (NERSC)
OSTI Identifier:
1405322
Grant/Contract Number:  
FG02-05ER15731
Resource Type:
Accepted Manuscript
Journal Name:
Catalysis Communications
Additional Journal Information:
Journal Volume: 52; Journal Issue: C; Journal ID: ISSN 1566-7367
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Platinum alloys; Surface segregation; Density functional theory; Catalysis; Oxygen; CO

Citation Formats

Herron, Jeffrey A., and Mavrikakis, Manos. On the composition of bimetallic near-surface alloys in the presence of oxygen and carbon monoxide. United States: N. p., 2013. Web. doi:10.1016/j.catcom.2013.10.021.
Herron, Jeffrey A., & Mavrikakis, Manos. On the composition of bimetallic near-surface alloys in the presence of oxygen and carbon monoxide. United States. doi:10.1016/j.catcom.2013.10.021.
Herron, Jeffrey A., and Mavrikakis, Manos. Fri . "On the composition of bimetallic near-surface alloys in the presence of oxygen and carbon monoxide". United States. doi:10.1016/j.catcom.2013.10.021. https://www.osti.gov/servlets/purl/1405322.
@article{osti_1405322,
title = {On the composition of bimetallic near-surface alloys in the presence of oxygen and carbon monoxide},
author = {Herron, Jeffrey A. and Mavrikakis, Manos},
abstractNote = {Periodic, self-consistent density functional theory calculations (GGA-PW91) are used to examine surface segregation in close-packed bimetallic Pt-overlayer alloy surfaces (Pt*/M, M = Au, Ag, Cu, Pd, Ir, Rh, Os, Ru, and Re) in different environments. In particular, we find that the thermodynamically stable surface termination in these Pt*/M alloys can be inverted from Pt-terminated in vacuum to M-terminated under exposure to oxygen (for an M that is more oxophillic than Pt). Interestingly, in many of these alloys, Pt is not driven into the bulk, rather it remains in the first subsurface layer where it enhances oxygen binding through a ligand interaction with the surface metal atoms. On the other hand, exposure to CO provides a much milder driving force for the surface composition inversion. To quantify segregation under catalytically relevant conditions, we constructed approximate phase diagrams for the PtRu systemas a function of O2 and CO chemical potential (temperature, pressure). Lastly, the results show that the surface termination inverts with many orders of magnitude higher CO pressure than with O2.},
doi = {10.1016/j.catcom.2013.10.021},
journal = {Catalysis Communications},
number = C,
volume = 52,
place = {United States},
year = {2013},
month = {10}
}

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